The present invention relates to novel mixtures having growth-regulating properties and more specifically relates to a novel growth regulating mixture of quaternary ammonium salts with growth regulating active ingredients in a suitable solvent. The invention further relates to methods for regulating plant growth.
Plant growth regulators (xe2x80x9cPlant Growth Regulatorsxe2x80x9d) serve many useful purposes in the areas of crop cultivation, agriculture and gardening. For instance, a particular concern in cultivating such crops as grain, corn, sunflowers and soybeans, is the problem of lodging of the plants due to unfavorable weather conditions prior to harvest. Inhibiting the longitudinal growth of the plants results in a thicker, stronger stem, thereby reducing the risk of lodging. Also, by inhibiting longitudinal growth of cotton crops, the course of maturation can be controlled in order to permit completely mechanized harvesting.
Growth regulation of fruit trees can result in reduced trimming costs, while also enabling the grower to restrict annual fluctuations in fruit tree yield.
Some Plant Growth Regulators can also be used to control the susceptibility of crops to adverse weather conditions by improving frost resistance. This is particularly useful in winter grain. Excess longitudinal growth and the development of overly lush leaves results in a more frost-vulnerable plant. It is also desirable to inhibit growth even during favorable growing conditions for example after sowing and before winter frosts begin. This results in a plant that is less vulnerable to frost. In addition to increased frost resistance, the relatively small leaf and plant mass become less susceptible to diseases such as fungus. Regulating growth of crop plants also enables many crop plants to be planted closer together resulting in a higher yield from a given area.
Quaternary ammonium salts, such as mepiquat chloride and chloromequat chloride, whose formulas are depicted below, are known Plant Growth Regulators. 
These compounds are commercially available in aqueous concentrates or in tablet or granule form (e.g. PIX(copyright) plant growth regulator, BASF Corporation). These compounds can be made by methods known in the art, such as, by converting secondary or tertiary amines with methyl halides. A method for water-free preparation of mepiquat chloride, which can be used as a solid charge stock in formulations, is described in European Patent Application, Publication No. 0 573 177 A2, incorporated herein by reference.
Other known active ingredients having growth regulating properties are described in European Patent Application, Publication No. 0 243 834 A2 and include the following formula: 
In this formula, the radicals have the following meanings: R1 and R2 independently of one another may be hydrogen, C1-C6 alkyl, C1-C6 halogen alkyl, C1-C4alkoxy-C1-C6 alkyl, C3-C6 alkenyl and phenyl, which may be unsubstituted or may carry one or independently of one another two or three of the following groupsxe2x80x94nitro, chloro, fluoro, C1-C3 alkyl, C1-C3 haloalkyl, and methylene dioxy; or R1 and R2 together with the carbon atom to which they are bonded form a 5- to 7-member ring, which in turn may carry one or independently of one another two C1-C3 alkyl groups; R3 may be hydrogen, a cation suitable for agriculture, C1-C8 alkyl, C3-C7 cycloalkyl, C1-C4 alkyloxy, C1-C6 alkyl, a CH2xe2x80x94C(O)xe2x80x94OR4 group, wherein R4 stands for C1-C8 alkyl, C3-C7 cycloalkyl, C1-C4 alkyloxy-C1-C6 alkyl, hydrogen or a cation suitable for agriculture.
Other active ingredients that have been described as possessing growth regulating properties include acylcyclohexadiones for example those described in U.S. Pat. No. 4,560,403, incorporated herein by reference, as represented by the formula: 
wherein R represents a hydrogen atom or an alkyl group, an alkylthioalkyl group or an unsubstituted or substituted phenyl group; and R1 represents an alkyl group, an unsubstituted or substituted benzyl group, a phenethyl group, a phenoxymethyl group, a 2-thienylmethyl group, an alkoxymethyl group or an alkylthiomethyl group, or a salt of said cyclohexane compound.
A specific compound for use as a growth regulating compound is prohexadione represented by the formula: 
As used herein, prohexadione includes the compound (IUPAC name) 3,5-dioxo-4-propionylcyclohexanecarboxylic acid (or 3,5-dioxo-4-(1-oxopropyl)cyclohexanecarboxylic acid (C.A. name)) and also 3-hydroxy-4-prionyl-5-oxo-3-cyclohexene carboxylic acid and its pharmacological effective salts for example a chloride, sulfate, metrab, acetate, carbonate, hydride, hydroxide, sodium, potassium, calcium, magnesium, barium, aluminum, nickel, copper, manganese, cobalt zinc, iron or silver.
Other acylcyclohexadione compounds having growth regulating properties are described in U.S. Pat. No. 4,693,745, incorporated herein by reference, and are represented by the formula: 
wherein
A is an xe2x80x94OR2 or xe2x80x94NR3R4 radical,
R is C3-C6 cycloalkyl,
R2 R3 and R4 are each independently hydrogen, C1-C6alkyl, C1-C6haloalkyl, C2-C10alkoxyalkyl, C2-C10alkylthioalkyl, C3-C6alkenyl, which is unsubstituted or substituted by halogen, C1-C4alkoxy or C1-C4alkylthio; C3-C6alkynyl; phenyl or C1-C6aralkyl, wherein the phenyl nucleus is unsubstituted or substituted by halogen, C1-C4alkyl, C1-C4alkoxy, C1-C4haloalkyl, nitro or cyano; one of R3 and R4 is methoxy; or
R3 and R4, together with the nitrogen atom to which they are attached, form a 5- or 6-membered heterocyclic ring system which may contain an additional oxygen or sulfur atom in the ring; and the metal or ammonium salts thereof.
Specific compounds of the immediately above noted formula include trinexapac (IUPAC name 4-cyclopropyl(hydroxy)methylene-3,5-dioxyocyclohexanecarboxylic acid) and preferably its ethyl ester, trinexapac-ethyl (IUPAC name, ethyl 4-cyclopropyl(hydroxy)methylene-3,5-dioxocyclohexanecarboxylate; CA name, ethyl 4-(cyclopropylhydroxymethylene)-3,5-dioxocyclohexanecarboxylate) represented by the formula: 
Mixtures of active ingredients with quaternary ammonium salts, such as those of formulations I(a) and I(b), are discussed in European Patent Application, Publication No. 0 434 613 A2. Although there mixture provide useful and beneficial properties, superior stability properties are sought for mixtures of active ingredients.
It is therefore an object of the present invention to create a formulation having growth regulating properties by combining the salt-like active ingredients of formulas I(a) and/or I(b), in a solution while simultaneously maintaining stability of the active ingredients. Another object of the present invention is to obtain growth-regulating properties by combining ingredients of formulas I(a) and/or I(b), with active ingredients of formulas III or with a acylcyclohexadione, and maintain the stability of the active ingredients.
The present invention provides formulations in which salt-like active ingredients, such as the quaternary ammonium salts of formulas I(a) and I(b), are dissolved in suitable organic solvents, in which other active ingredients with growth regulating properties, such as those of formula III, IV or V, can also be added while maintaining adequate stability of the active ingredients. While it is known that salt-like active ingredients such as quaternary ammonium salts are soluble in water, due to their polar, salt-like and inorganic characteristics, such aqueous solutions may cause degradation of other active ingredients used in growth regulating mixtures.
It has been found, surprisingly, that the salt-like formulations I(a) and I(b) are suitably soluble in organic solvents having either of the following two formulas which are referred to herein as formulas II(a) and II(b) respectively: 
or 
wherein
xe2x80x9cRxe2x80x9d is Hydrogen or a C1-C18 alkyl,
xe2x80x9cnxe2x80x9d is 0, 1, 2 or 3,
xe2x80x9cAxe2x80x9d is a C1-C6 alkene or a C1-C6 oxyalkylene,
xe2x80x9cmxe2x80x9d is 1, 2, 3, 4 or 5, and
xe2x80x9cBxe2x80x9d is a straight-chain or branched C2-C8 alkylene.
While these solvents provide adequate solubility of salt-like active ingredients of formulas I(a) and/or I(b), they also are good solvents for active ingredients of formulas III, IV and V. Moreover, use of these solvents has been found to result in very good stability of active ingredients in solution. Particular advantage may be found by combining the salt-like active ingredients of formulas I(a) and or I(b) in combination with compounds of formulas III, IV and/or V. Growth regulating properties are attained and the mixtures adequately sustain the stability of the active ingredients. These formulations are preferably provided in the substantial absence of water.